Glass ceramic materials

ABSTRACT

A METHOD AND APPARATUS FOR MANUFACTURING GLASS CERAMICS FROM CRYSTALLIZABLE VITREOUS MATERIAL ARE DISCLOSED, IN WHICH THE TEMPERATURE OF THE VITREOUS MATERIAL IS REGULATED TO A VALUE AT WHICH UNIFORM DISPERSION OF EMBRYONIC CENTERS OF INCIPIENT CRYSTAL GROWTH IS GENERATED THROUGHOUT THE MATERIAL AND THE MATERIAL IS SUPPORTED ON A HOT GASEOUS SUPPORT, AND THEREAFTER THE MATERIAL IS RAPIDLY HEATED ON ITS GASEOUS SUPPORT TO A CRYSTALLIZATION RANGE OF TEMPERATURE AND HELD IN THAT RANGE ON THE GASEOUS SUPPORT TO TRANSFORM THE MATERIAL TO A GLASS CERAMIC BY FINEGRAINED CRYSTAL GROWTH ON THOSE CENTERS. THE GASEOUS SUPPORT MAY BE PROVIDED BY HOT GAS DIRECTED THROUGH PER-   FORATED TILES ON TO THE UNDERSIDE OF THE MATERIAL. HOT GAS MAY BE DIRECTED ON TO BOTH SIDES OF THE MATERIAL TO EFFECT THE RAPID HEATING OF MAINTENANCE IN THE CRYSTALLIZATIONS RANGE, WHILE THE MATERIAL IS SUPPORTED BY THE GAS DIRECTED AT IT FROM ONE SIDE. THE THERMAL PROCESSING MAY BE EFFECTED IN A CONTINUOUS MANNER IN A FURNACE DIVIDED INTO A CENTER-GENERATING ZONE, A GRADIENT ZONE, A CRYSTALLIZATION ZONE AND A COOLING ZONE.

Ma 7, l974 TH ETAL 3,8D9,542

GLASS CERAHIC MATERIALS Filed Feb 15 1972 4 SheetS-Sheet 5 9 10 rowth isenerated, advancin the ribbon alon the ase- 3,223,Sol 12/196S Fredle etal 6S33 X Ous suppoft and heating the advancing n1aterial rapidly3,499,773 3/ 1970 I etticrevv et al 633 x to the crystallization rangeand maintaining the ribbon at 3,48j,644 12/1969 Shonebarger 6S33 x thattem erature while it continues to advance, and then OTHER REFERENCEScooling the ribbon of glass ceramic material S0 formed Handb00k of GlassManufacture, V01. II, Fay v. pnor t0 Een10vlng ltfron1 the gaseoussupport. Tooley, odgen pub" 1960' References Ced UNITED STATES PATENTS3,464,807 9/ 1969 Pressau 633 X 10 U.s. C1. x k( 3,4S3,3Sz 7/l969Goundry 633 x 6182 A, 65

FRANK W MIGA, Primar Examiner

